Sharing Data Among Packages
In previous chapters, we established that each package runs in its own process. All assets that are installed or created through this package belong to the user whose ID is assigned to the package. You also know that Android allocates a unique Linux-based user ID to run that package. In Figure 16–1, you can see what this user ID look like. According to the Android SDK documentation
This user ID is assigned when the application is installed on the device, and remains constant for the duration of its life on that device. Any data stored by an application will be assigned that application's user ID, and not normally accessible to other packages. When creating a new file with
getSharedPreferences(String, int), openFileOutput(String, ...